ardupilot/libraries/AP_Filesystem/AP_Filesystem_Param.h

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/*
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#pragma once
#include "AP_Filesystem_backend.h"
#include <AP_Common/ExpandingString.h>
#include <AP_Param/AP_Param.h>
class AP_Filesystem_Param : public AP_Filesystem_Backend
{
public:
// functions that closely match the equivalent posix calls
int open(const char *fname, int flags) override;
int close(int fd) override;
int32_t read(int fd, void *buf, uint32_t count) override;
int32_t lseek(int fd, int32_t offset, int whence) override;
int stat(const char *pathname, struct stat *stbuf) override;
int32_t write(int fd, const void *buf, uint32_t count) override;
private:
// we maintain two cursors per open file to minimise seeking
// when filling in gaps
static constexpr uint8_t num_cursors = 2;
// only allow up to 4 files at a time
static constexpr uint8_t max_open_file = 4;
// maximum size of one packed parameter
static constexpr uint8_t max_pack_len = AP_MAX_NAME_SIZE + 2 + 4 + 3;
static constexpr uint16_t pmagic = 0x671b;
// header at front of the file
struct header {
uint16_t magic = pmagic;
uint16_t num_params;
uint16_t total_params; // for upload this is total file length
};
struct cursor {
AP_Param::ParamToken token;
uint32_t token_ofs;
char last_name[AP_MAX_NAME_SIZE+1];
uint8_t trailer_len;
uint8_t trailer[max_pack_len];
uint16_t idx;
};
struct rfile {
bool open;
uint16_t read_size;
uint16_t start;
uint16_t count;
uint32_t file_ofs;
uint32_t file_size;
struct cursor *cursors;
ExpandingString *writebuf; // for upload
} file[max_open_file];
bool token_seek(const struct rfile &r, const uint32_t data_ofs, struct cursor &c);
uint8_t pack_param(const struct rfile &r, struct cursor &c, uint8_t *buf);
bool check_file_name(const char *fname);
// finish uploading parameters
bool finish_upload(const rfile &r);
bool param_upload_parse(const rfile &r, bool &need_retry);
};